1. Field of the Invention
This invention relates generally to elevators for buildings, and particularly to the hoistways, or elevator shafts, within buildings wherein elevators move between floors. More particularly, this invention relates to a free standing hoistway frame for elevators which may be installed in modules to replace a structural building hoistway to enclose the elevator.
2. Description of Related Art
Elevators come in several designs: traction, cantilevered and piston types being among them. Though some are exposed on exterior or atrium walls for the views they provide passengers, most are located within the interior of buildings and surrounded by a structural hoistway, a cylindrical shaft extending vertically through multiple floors with openings onto floors for elevator doors. Elevator hoistways built during and as part of building construction typically comprise concrete, brick or fire resistant wall board surrounding the hoistway. Among other things, the hoistway isolates the elevator from the remainder of the building floors as a fire safety measure.
Within the hoistway are housed the equipment and devices needed to operate the elevator, including guide rails, lifting mechanisms and floor doorway sills upon which the sliding doors of both the elevator car and the floor articulate. With currently conventional construction, wooden beams embedded within the hoistway walls provide attachment points for the elevator contractor's use when installing such equipment. The hoistway must be built first, before the elevator guide structures are installed, and it typically is done by different contractors.
This approach has several disadvantages. The wooden beams chronically are not installed accurately enough for the relatively precise erection of the elevator and its guides. Elevator contractors later must make unforseen and expensive adjustments, potentially causing delays and added costs. Obviously, the practice also requires that the hoistway be constructed first, requiring the elevator contractors to contend with the relatively confining space within the hoistway. This in turn affects the approach to assembly of the elevator guide structures, which must be brought into the building piecemeal and assembled in place. A need exists for a self-supporting, adjustable hoistway and guide system which may be installed in advance of building erection.
Older buildings with elevators that need replacement often have hoistways that are considerably larger than current elevator design requires. In such cases, the hoistway must be modified, often at great expense, to fit the new equipment. A need exists for a prefabricated elevator hoistway that can fit inside of older, larger shafts in retrofit elevator installations.
A few prefabricated elevator supports and guide cages have attempted to address these problems. For example, Bass, et al., U.S. Pat. No. 7,261,184, provides a free-standing elevator support structure that is adapted to couple to the building only as needed for stability. Bass ('184) is incapable of substituting for the elevator hoistway itself, however, and depends instead upon the hoistway being in place when Bass' structure is erected. A need exists for a self-supporting elevator hoistway cage that can be erected before a building is erected around it, and which is adjustable to accommodate irregularities in said building after completion.
Similar needs exist for multi-floor building stairways. Though such stairway flights commonly are prefabricated, they must attach to the building for support and stability. A single flight of stairs is a relatively large object which, under current practice, must be maneuvered into a relatively tight pre-existing stairwell. If the stair flights could be erected along with a free-standing stairwell to contain them, efficiencies and time and construction costs could be realized.